This invention relates to an X-ray photography apparatus used for X-ray diagnosis, more specifically to an X-ray photography apparatus used for X-ray diagnosis of the circulatory system.
In an X-ray diagnosis of the circulatory system, it is necessary to photograph X-ray images of blood vessels distributed over a widge range covering substantially all parts or regions of a subject or a patient, including the heart, coronary arteries, brain, abdominal region, lower limbs, etc. In the photographing or filming, the patient must be X-rayed along the course best suited for the diagnosis, and an image receiving device need be positioned and oriented in an optimum manner. An X-ray diagnosis of blood vessels of the heart, for example, requires the use of a first photographing method or cross-directional photographing method and a second photographing method or longitudinal directional photographing method. In the first photographing method, X-rays are projected on the part of the patient to be photographed or filmed on a cross direction normal to the body axis of the patient, in various directions, i.e., in frontal, lateral and many oblique directions. In the second photographing method, X-rays are projected on a longitudinal direction containing the body axis of the patient in the direction substantially normal to the body axis and in many other directions at angles to the normal direction. The cerebral artery, such as the carotid, is photographed from the front of the patient by a third photographing method or Towne method in which an X-ray beam is projected from the forehead side with its central axis at an angle to the orbit metal basal line. To avoid exposure of the crystalline lens, a fourth photographing method has recently been used, in which an X-ray tube is moved to be located under a table carrying a patient and radiates X-rays from under. According to the fourth photographing method, the X-ray must be radiated in the opposite direction to that for the Towne method. In taking an X-ray photograph of blood vessel distributed in the lower limb of a patient, a fifth photographing method is executed in which an X-ray tube and an image receiving device are shifted intermittently in parallel with each other over the lower limb region. In any of the five photographing methods, the image receiving device should naturally be located in a suitable position relative to the course of X-ray radiation.
The photographing X-ray images of the circulatory system positively requires cine-filming for some objects of diagnosis, but needs only the normal direct photographing method for others. The cine-filming is needed in the diagnosis of those parts, such as the heart and the coronary arteries, of which it is quite essential to observe the motion. The cine-filming is performed by using a cinecamera for shooting an X-ray image intensified by an image intensifier (hereinafter referred to as an I-I section). Since the cine-filming need, however, be executed while monitoring the target regions, so it requires the use of a television unit as well as the cinecamera, and the X-ray image delivered from the I-I section is received by a vidicon. The cine-filming is unnecessary for the diagnosis of those blood vessels, such as those of a brain, the abdominal region, the lower limbs, etc., in which blood flows extremely slowly. In this case, direct photographing is often performed with use of a film changer (FC).
Thus, the X-ray photography apparatus used in the diagnosis of the circulatory system is expected to fulfill many requirements as follows. Since the target regions are distributed throughout the whole body of a patient, the X-ray tube and the image receiving device are desired to be moved over a wide range substantially to cover at least the half length of the stature of the patient. Moreover, X-rays need be projected on the target regions via various courses, and the X-ray receiving direction of the image receiving device should be varied with the course of X-ray radiation. Furthermore, the apparatus need be able to switch from the cine-filming to the direct photographing with ease.
These requirements are attributable to the circumstance that the diagnosis of the circulatory system often requires close attendance of an assistant and the use of various auxiliary appliances or devices, so that the assistant and the auxiliary appliances or devices need be moved along with the patient who is moved between the X-ray tube and the image receiving device to be examined at various parts. Such awkwardness may be eliminated by enabling the X-ray tube and the image receiving device to move over the range substantially to cover at least the half length of the stature of the patient.
Various X-ray photography apparatus have been developed to meet the aforementioned needs. Heretofore, however, no apparatus has been provided yet which can fulfill all those requirements singly. This is so because the conventional apparatus would not be able to control independently the position and X-ray radiating direction of the X-ray tube, as well as the position a direction of the image receiving device, as desired.